starting issues, and erratic acceleration

[1moreMPH]

as of recent, the MSP has been difficult to start on more than a few occasions. It does not seem to be affected by whether the car is cold or warm, but it did start when the weather dropped down cold.

When i turn the key, the car will (slowly) try to turn over and keep turning over, but will not start. I usually do this 2-3 times, and then it will eventually catch and start. Driving seems to be completely normal in and out of boost. i replaced the spark plugs at the end of the summer.

Also, i don't know if this could be related or not, but yesterday as i was merging onto the highway, i dropped it down to 2nd gear at about 40mph so i could get up to speed and around the trailer in front of me. As soon as i did so i punched it pretty hard, and the car at first lurched forward as normal but only for a split second. Then it completely shut down as if i slammed on the brakes for a second, then resumed acceleration, then stopped again, and finally went on normally. It was an incredibly jerky happening -- just to emphasize, my head was probably close to hitting the wheel/windshield when it jerked like this. Afterwards, the car ran normally accelerating/boosting/normal driiving and everything. Im not sure if this was a problem, maybe it was just the clutch not catching or something.

Anyways, if anyone has any guesses, toss them out. Im more concerned about the not starting issue since she drove normal all yesterday after that little problem.

performance includes: cai, fmic, hks bov, apexi catless, Sam-tuned Unichip @ 9psi, front motor mount. afr appears normal (narrowband), and boost seems normal as well.

 

[mazdaspeedson]

for the starting problems it sounds like you live somewhere cold the protege i well known for being a hard start in the cold even the n/a ones try to keep it in a garage if at all possible. as for your hesitation i had a similar problem with one of my coil packs going bad it was like hitting a brick wall it sucked if it is a coil pack then it will get worse as time goes on adventually throwing a check engine light at that time you will know which one to replace because your car has 2 the computer will tell you which cylinders are misfiring if the problem stops and never comes back sounds like fuel cut

 

[NCZ13]

i think the starting issue has to do with the battery. my p5 was turning over veeeeerry slowly, and soon it stopped turning over if i left the headlights on for a minute.

i got a new battery, youll be amazed at the difference it makes.

 

[1moreMPH]

my first thought was battery as well, but all the lights and radio work find with no dimming with the car off. so i think that x's out the battery. It could be the alternator, but in that case i feel it would be consistently getting worse, which it's not; sometimes it turns slow and i have to try a few times, sometimes it starts right up. I guess i'll turn down the boost a bit for safety and keep on driving, maybe the CEL will come on to indicate a dead coil...

 

[1moreMPH]

unfortunately i am not one to know much about clutches... but could the acceleration issue be due to the factory clutch not engaging correctly? I am pushing significantly more hp out of the engine than it comes stock, so could that cause the clutch to slip at all if i slam it to the floor while shifting to second?

 

[BOOSTR]

Don't think you have a clutch issue.
Have you tested your battery with either a load tester or multimeter to see how many volts its putting out? Test it and also make sure that all of the wires/connections are good. How's your vacuum at idle?

 

[NCZ13]

my old battery had enough juice to operate all the electronics in the car,but it didnt have enough juice to turn the engine over.

maybe this could be your case?

 

[greasemonkey524]

Your starter could also be the culprit. It might have a bad spot if it cranks slow sometimes.

 

[1moreMPH]

i'll see if i can't check the battery tonight just to be sure. idle is normal, between 20-22 mm-Hg.

all my pipes appear to be connected, and i tightened everything down, maybe the jerky-ness upon accelerating was some fluke thing. It was just so harsh that it scared the s*** out of me. I mean it went from FLOORING it in 2nd at ~40mph, to SLAMMING on the brakes, then Flooring at 45, SLAM on brakes, then shift to 3rd and go on my business...

another thing about the start-up: would colder plugs affect anything there?

 

[crashkelly]

unfortunately i am not one to know much about clutches... but could the acceleration issue be due to the factory clutch not engaging correctly? I am pushing significantly more hp out of the engine than it comes stock, so could that cause the clutch to slip at all if i slam it to the floor while shifting to second?

how much hp are you pushing...if you only have a unichip, exhaust and cai it is not that much more than stock? i mean minus the 30rwhp banner...and i hope that you know rwhp means rear wheel hp...

 

[BOOSTR]

Good deal on the VAC, so nothing is leaking. Thought that might be a possible cause for your stumble. Heat range of the plug would not affect start up. A mystery quirk sure would not be a first for a MSP!

If you check the battery with a multimeter, do it both cold and then start the car. Should be over 12.0 cold and over 14.0 when running. I'm still on my stock battery and it puts out 12.6 cold and 14.12 running. I'm shocked by this at this point that its still holding out after all of this time.

 

[crashkelly]

the onlyother suggestion i can think of is make sure that your terminals are secure on the battery posts. When i got my msp the terminal clamps were always loose and they even came off while driving once causing the car to die right on the road...lost power steering and everything. Prior to them actually coming off there were issues with the connectivity...i did occasionally get a stumbling because the terminal would come loose then contact the post properly and come loose and so on. Everytime it happened it was acting like the car was going to stall out. I could have sworn I had a vac leak..but it definately was the terminal ends...they looked like they fit, but they were a hair too big.

 

[1moreMPH]

how much hp are you pushing...if you only have a unichip, exhaust and cai it is not that much more than stock? i mean minus the 30rwhp banner...and i hope that you know rwhp means rear wheel hp...

my guess is ~240whp. The unichip is custom-tuned with VERY advanced timing at 9.5psi, the exhaust is 3" catless, and i also have fmic. lol -- and yea i know about rwhp, glad you caught the joke lol.

 

[dmention7]

The lurching sounds like fuel cut. I had the same thing happen to me once in the summer--I made an abrupt downshift to 2nd, and as soon as I hit full boost, I got several violent lurches that felt exactly as you described. From what I've read, that's textbook fuel cut.

 

[crashkelly]

my guess is ~240whp. The unichip is custom-tuned with VERY advanced timing at 9.5psi, the exhaust is 3" catless, and i also have fmic. lol -- and yea i know about rwhp, glad you caught the joke lol.

damn you made a lot of power with that chip huh? I am going on friday to get a custom dyno tune from Mike Mahffey(spell check?) at Altered Atmosphere. I was hoping just to make like 225-230, but i have similar mods to you so hopefully I can get some more out of it. As for your problem have you changed your map to see if there was any difference? Or is your b map just a WOT change in timing?

 

[mspHtown]

the lurching definitely sounds like fuel cut. you said that everything feels fine and runs the same in and out of boost right? also, you said the temperature dropped as well. i hit fuel cut on stock boost a long time ago and it freaked me out. when i turned the boost up some and tuned it with the MPI, i hit fuel cut quite a few times. the car ran fine in and out of boost, but occasionally when i got on it(and its cold outside), it felt like i was hitting a brick wall. when i switched to my current setup with the fuel cut defender, i have never experienced fuel cut again.

 

[JDM Sam]

Turn the boost down and try to get a scan tool to log the MAF voltage.

 

[1moreMPH]

see but ive had fuel cut before when i was on the stock computer, and this is so much more violent. Fuel cut that ive experienced is just 0 acceleration, more like the engine hits a wall and stops moving you forward. This was like THE CAR BODY hit a wall, as in it actually slowed down like i slammed on the brakes. I guess it could have been fuel cut, but i have never fealt it like that before.

Last night i reset the ecu, turned down to stock boost and went out to run around in it. Everything seemed normal, under all sorts of driving conditions so i upped the boost back to 10psi. Again drove under all sorts of acceleration, all gear pulls, drops.. I beat on it for quite awhile; and everything seemed normal. The only thing i noticed was that i didn't spin through 2nd like normal, and i didn't spin into third. However, this is the first time ive really ragged on it since i got new (read: much stickier) tires.

Sam -- is this the same sort of scan tool found at autozone and such? What should i look for in the log?

 

[JDM Sam]

Something that can read the MAF voltage from the OBD2 port. Some lower end scan tools can't. The PC scan tools work.

 

[1moreMPH]

ive asked around and no one i know has one. im going to assume that she's ok. After resetting and driving around for a few days now, nothing abnormal has come up since. vac/boost/idle/afr all seem ok and ive been out pushing the car pretty hard a few times. Im also beginning to think the starting issue may have to do with the cold because when it does warm up a little midday, it starts ok.

If all is hopefully well, im going to be headed to the track on the 8th for some quarter-mile action. Sam -- you think the tune will respond well to race gas? I remember you saying that if i wanted to get any more power at all out of her that race gas was the way to go, but i don't know how serious that was. I think i can get my hands on some 103 octane, and that could be fun.